The fast recharge that will one day restore the autonomy of electric vehicles in 5 minutes is of space derivation: it is due to a research group at Purdue University, sponsored by the biological and physical sciences division of NASA.
The system has already conceptually demonstrated that it can work and is being tested on the International Space Station: the issue of recharging electric vehicles is obviously not only a terrestrial issue, but also a critical issue regarding future missions to the Moon and Mars.
Physics and everyday life confirm that the increase in performance is accompanied by an increase in temperatures and consequently everything the implant requires oversizing: The charging cable itself needs large conductors. The goal is to reduce operating temperatures without serious side effects on the size of the implants or the weight of the hardware component.
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How the system works
The group led by Professor Issam Mudawar of Purdue’s Mechanical engineering department has started working on an evolved cable concept in 2017, in collaboration with Ford. The first version was presented in 2021, then the platform for the Flow Boiling and Condensation Experiment (in acronym Fbce) was created for the management of heat transfer in a microgravity environment. Practically a variation of the project for the ISS: a boiling module which “includes heat generators mounted along the walls of a channel in which the refrigerant is supplied in the liquid state”.
With the gradual heating of the devices, the temperature in the channel rises and the liquid adjacent to the walls begins to boil; the bubbles generated allow you to quickly transfer the heat “by exploiting both the lower temperature of the liquid and the consequent phase change from liquid to vapor”. The best results are obtained when the liquid is “in a supercooled state (well below the boiling point, ed)”. The concept refers precisely to the so-called boiling under cooled flow.
The Fbce was handed over to the ISS in August 2021 and the first data emerged from the beginning of 2022: the experimentation will continue, but in the meantime on Earth there is the conviction that a migration of technology in the industrial sector is possible, precisely in the electric automotive sector.
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The application in the automotive field
The actual electric charging of automobiles in addition to the theme of the number of balusters, is conditioned by at least two key factors: the capacity of the batteries mounted on the vehicles measured in kilowatts / hour and the charging power of the stations measured in kilowatts. Dividing the first by the second one obtains a probable theoretical data on the times. And so it turns out that it takes about 5 hours to recharge a Nissan Leaf on a classic columnwhile at home (in the worst case scenario) it can be up to 17 hours, depending on the systems and powers involved.
One of the nodes of the charging systems concerns the cable that connects the station to the vehicle: le versions used for fast charging are 350 amps and involve the use of large conductors. They are very uncomfortable, in short. To reach the desired threshold of 5 minutes (which in reality the whole industry aspires to) it would be necessary to reach 1400 amps (775 kW), but NASA recalled that “the most advanced chargers only supply up to 520 amps of current and most of the chargers available to consumers support up to 150 amps. “
So the solution could be to rely on a non-conductive coolant, pumped through the charging cable. This heat dissipation system would provide 4.6 times the current of current high performance (520 amp) chargers on the market, removing up to 24.22 kilowatts of heat: “The charging cable Purdue can deliver 2400 amps, well beyond the 1400 needed to reduce the time it takes to charge an electric car to 5 minutes, ”NASA noted.
It should be emphasized that this technology only represents the first step towards hyper-fast chargingsince a new generation cable should also be accompanied by a battery and a power supply of adequate power: “The experiments and results of NASA with Fbce inspired some aspects of our electric cable cooling experiments, in particular contributing to our know-how technician on this physics – confirmed Mudawar to The Register – We are currently working with several automotive component manufacturers to further improve and implement this technology. “